The present invention relates to anesthetic/gas delivery apparatus for delivering anesthetic to a patient during surgery, and more particularly for delivering anesthetic to a patient during plastic surgery.
In the sequence of events of drug-induced depression of the central nervous system there occurs a level of depression that allows the muscles of the pharynx (e.g. the tongue) to relax causing soft-tissue structures to collapse into and obstruct the airway. This happens at an earlier stage than that at which the muscles of respiration (e g. the diaphragm) cease to function. In other words, the condition known as xe2x80x9cobstructive apneaxe2x80x9d, where the diaphragm is struggling to pull air through an obstruction of the upper airway occurs before the diaphragm, itself, ceases to function (xe2x80x9ccentral apneaxe2x80x9d). In this sequential depression of the central nervous system, death occurs from asphyxia before the drug, itself, can produce complete depression of the nervous system.
This condition of obstruction occurs upon the induction of almost every general anesthetic and is a frequent occurrence during the administration of heavy sedation for procedures done nominally under xe2x80x9clocal anesthesia with sedation. xe2x80x9d Under most conditions the treatment is so routine as to be taken for granted by practitioners skilled in airway management. Manual support of the airway, application of a face mask over the mouth and nose and various airway devices are employed, often with supplemental oxygen.
Recent advances in cosmetic surgery, however, have made airway management significantly more challenging and have caused practitioners to accept conditions having a reduced margin of safety for their patients. In particular, LASER procedures on the face are requiring heavier sedation leading more often to respiratory depression and obstruction while, at the same time, the increased fire hazard restricts the use of oxygen.
Observations of drug-induced respiratory dysfunction and its treatment can be characterized as a Syndrome of Narcogenic Obstructed Respiration (SNOR). The syndrome is characterized by the following features. Firstly, a drug-induced depression of the central nervous system is caused, which secondly leads to an acute and complete upper airway obstruction, and which thirdly can lead to asphyxia and death.
SNOR is preventable by applying positive pressure through the nasopharynx while leaving the oral cavity open to ambient pressure. The pressure differential thus created splints the soft tissues out of the airway with a natural pressure relief valve through the oral cavity. The maximum pressure obtainable is consistently sufficient to relieve the obstruction, but less than the 20 centimeters of water that might send air to the stomach.
This concept is new to the thinking of anesthesia practitioners, who traditionally apply a face mask as a first-line remedy of upper airway obstruction. However, the standard face mask places pressure on the chin and tends to collapse soft-tissue structures of the oropharynx. Additionally, air pressure that is applied through the face mask tends to equalize through the nose and the mouth, and therefore it can be counter-productive to the stenting-up of soft tissue to open the airway. Further, using a face mask usually requires one or two additional maneuvers, for example manual support of the chin, the insertion of an oral airway, etc., in order to remedy the problem.
The treatment of Obstructive Sleep Apnea (OSA), a syndrome defined in the early 1980""s, has demonstrated that upper airway obstruction occurring during the sleep of afflicted patients can be relieved by the application of positive pressure through the nose alone. The present inventor has recognized that this can be of significant usefulness in cosmetic surgery practice.
Accordingly, it is an object of the invention to provide an anesthetic delivery apparatus which can provide Continuous Positive Airway Pressure (C-PAP) through the nose in order to prevent an upper airway obstruction.
OSA is similar to SNOR in anatomy and treatment, but differs in that it is not drug-induced, with acutely disastrous consequences, but rather is a chronic condition with long-term ill-effects. SNOR is treated according to the apparatus of the present invention by modified application of C-PAP as used in obstructive sleep apnea.
A gas delivery apparatus according to the present invention includes a nasal airway having a gas passage therein for insertion into the nose. A swivel is connected to the nasal airway, the swivel having a gas passage therein communicating with the gas passage of the nasal airway. Tubing has a proximal portion connected to the swivel so as to be in fluid communication with the gas passage of the swivel. The tubing bends so that an angle is formed between the distal portion of the tubing and the proximal portion of the tubing.
The nasal airway may comprise a rubber naso-pharyngeal airway, or may preferably comprise a nasal vestibular portion that is adapted to fit in a nasal vestibule. The nasal vestibular portion has a connection part that connects the nasal airway to the swivel. The nasal vestibular portion flares outwardly with respect to the connection part, and the gas passage of the nasal airway extends through both the connection part and the nasal vestibular portion.
The nasal vestibular portion comprises a superior pole for engaging the apex of a nasal vestibule. Further, an inferior pole of the nasal vestibular portion is provided to engage an inferior nostril rim of the nasal vestibule. The superior pole is elongate and rounded, and the inferior pole comprises an angled wedged shape. Thus, the superior pole, lodged in the apex of the nasal vestibule, helps to direct the inferior pole with the angled wedge shape against the inner surfaces of the nose to push the surfaces outward, thereby sealing.
The nasal vestibular portion may comprise a flexible material. In this case, a thin flap can be provided around the perimeter of the nasal vestibular portion for providing further sealing with the nasal interior.
A second nasal vestibular portion can be provided to connect with the second nostril of a patient. The second nasal vestibular portion also flares outwardly with respect to the connection part. In this instance, the connection part has one portion in which the gas passage of the connection part is connected with the swivel, and another portion in which the gas passage of the connection part branches into two gas passages communicating with the first and second nasal vestibular portions.
The tubing can include a plurality of swivels to provide for the ability to swivel the tubing not only from side to side, but also from the upper to the lower position with respect to the patient""s head. The head strap and/or an ear hook may be connected to the tubing to hold the tubing on the head of the patient.
A nasal plug can also be adapted to close one nostril when only one nasal airway is supplied with gas. The nasal plug may be similar to the nasal airway which comprises a connection part and a nasal vestibular portion, but in this case would have its gas passage blocked, for example by a cap. Alternatively, the cap could include a small opening to receive an oxygen tube to provide oxygen to the nostril.
The tubing may also have vent holes therein. Further, it may be bent so as to form an acute angle between the proximal portion and the distal portion.